Casting process and apparatus



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- R. F. WOOD CASTING PROCESS AND APPARATUS Filed Aug, '7, 1919 5 Sheets-Sheet 2 WWWI- April 1'4,l 1925. 1,533,780

R. F. WOOD CASTING PROCESS AND APPARATUS Filed 15ggE v, 1919 5 snee'qslsneet s April 14, 1925.

Fiied Aug. v, 1919 5 sheets-sheet 4 uw @wlw April 14, 1925.

R. F. WOOD CASTING PROCESS AND APPARATUS Filed Aug 7, 19.19 5 Sheets-'Sheet 5 Patented Apr. 14, 1925.

UNITED STATES PATENTcorriges.;

ROBERT F. Woon, or SANDUSKY, OHIO, AssIGNoa To `THE rArEaa TEXTTLEMAOHIN'- EBY COMPANY, or SANDUSKY, OHIO, A CORPORATION OF OHIO.

CASTING PROCESS AND APPARATUS.

vApplication ledvAugust 7; 1919. Serial 110.315,892.

To all whom t may concern:

Be it known that I, ROBERT F. VooD, a citizen of the United States, residing at Sandusky, in the county of Erie and State of Ohio, have invented certain new and useful Improvements in Casting Processes and Apparatus, of which the following is a speciication.

My invention relates to an improved process and apparatus for making castings of metal or of other material and is particularly applicable to the making of hollow or tubular objects having non-cylindrical bores.

The object of my invention is the provil5 sion of a new and useful casting process.

Other objects of my invention are: The provision of apparatus suitable for carrying out my process; the provision of aprocess whereby hollow or tubular castings may be produced without the. use of cores of sand or of other. solid material; the provision of a process for producing a castinghaving a paraboloidal void, from which casting there may be made, by machining in a lathe or by other process of manufacture, a hollow or tubular article whose bore or void, though' not itself paraboloidal in shape, may be more or less approximated in shape and size by the paraboloidal void ofthe casting; the 3o provision of a process for producing castings for submarine periscope tubes and cones; and the provision of a centrifugal process whereby a hollow or void of predetermined paraboloidal shape may be formed -in cast- :25 ing an object without the'use of a solid core. My invention is particularly useful in the productionof submarine periscope tubes and cones in which it is necessary that one end be of smaller diameter than the other, and that the metal be of uniformly good quality free from blow holes, internal strains and such other imperfections as are common to tubes made by certain other methods of casting and manufacture.` My invention may also be used for casting hollow projectile shells. 4I do not limit the uses to which my invention may be put as 'numerous applications will occur to` thosel skilled'in the various arts in which hollowor tubular parts 5o are used. In the accompanying drawings I have illustrated one form of apparatus which has proved suitable for carrying. out my process.

In the drawings, Fig. 1 is a side elevation of a casting machine suitable for carrying e may be calculated in advance for any given HEISSUED out my process; Fig. 2 is a vertical *frag mentary cross section through the upper end of'the mold on line II-II ofl Fig. 3; Fig.

3 1s an end elevation of the front or righthand end of the machine showniny Fig. 1; 60 F 1g. 4 is an end elevation of the rear or left hand end of the machine shown in Fig. 1';

F 1 gs. 5, G, 4' and 8 are diagrams for proving the theory o-f my process; Figs; 9 to 17 inclusive are longitudinalv sections through paraboloids generated by parabolasfof different equations; and Figs-18, 19 and 20 are longitudinal crosssections of various castings suitableI for making submarine peri-' scope tubes. 70 In carrying out my process I introduce a quantity of molten metal or of other solidifiable material into' a'hollow mold of metal or of suitable refractory material, the'quan tity of molten metal being insufficienttofill the mold. 'Ihe mold is preferablylirst inclined so that its axis makes a known angle with the horizontal, and is given a rapid rotating motion ofknown speed about its axis while in this inclined position. Inmaking S0 a metal casting the molten metal is introduced into the mold preferably While it is rotating. Under the action of centrifugal force and yof gravity the metal iows and forms a hollow shell, lining the interior. surfacey of the mold. Atdii'erent speeds of rotation or at different angles of inclination ot the axis of the mold, or both, bores or voids of different shapes are formedv in thevmolten metal. I have discovered and demonstrated. however, that the shape of thehollow or void formed in the liquid or rnolteumaterial is independent of the shape of the mold and is always a paraboloid of revolution or some part thereof, the shape and dimensions of which are determined by the size of the mold, its speed of rotation, the angle of inclination` of the axis of rotation andthe quantity of metal in the mold. :I -have proved mathematically and have demonstrated in practice by making numerous castings that there are .delinitelyvxed relations between these factors; that. the shape and dimensions of the hollow or bore in a casting size of mold, speed of rotation, angle of inclination, and quantity of metalg, and that when the size of the mold and| the essential dimensions of the required hollow or bore are `given, the speed of rotation of the mold,

its angle of inclination, the quantity of metal vto use and the shape of bore that will result may be predetermined by calculation.

It is to be understood that in these specifications the term inclined or inclination comprises any position other than horizontal up to and including ninety degrees where the axis of the mold4 would be vertical.

In .carrying out my process, the speed of rotation of the mold and the angle of itsiinclination, or both, may remain constant throughout the entire period of pouring, casting and solidifying, but I do not consider that this is' essential in all cases. It-"is evident that in order to produce a simple parabolo-idal void of predetermined shape, the metal must be maintained in a state of equilibrium whileit passes from the molten to the solid condition, and this state of equilibrium is most readily 'obtained by keeping the speed :of rotation and the angle of inclination constant. However, it is conceivable thatthere might arise conditions under` which the process by which the rough casting is subsequently to be treated or the purpose for which it is to be used would be better served if the casting process were so controlled as to modify more or less the otherwisel simple paraboloidal shape 4of the boreof the casting.

It is furthermore evident that if the speed.

for angle be changedat a moment when spite of such' change in speed or angle,

the process of solidification of the metal is as yet incomplete, the portion Vof the metal which has bythat time,already become solidified will retain its position in while the portion ofthe metal which is still molten or semi-molten will flow or tend to iow inl such a, way as to readjust itself to the new conditions, .and,. under them, to

reach. a new position and a new state of equilibrium. In my experience with the practical carrying out of my process I have already encountered conditions"such as -I have described, and I have encountered instances in which the subsequent processes of machining-the casting'in a lathe were facilitated by having the otherwise-simple' paraboloidal shape of the bore of the casting modified in accordance with the foregoing. It is therefore conceivable that other instances also may'arise in which the purposes or treatment ofthe casting will bebetter served by the modifications de scribed or by other modifications similar thereto, and it is one of the advantages of my process that in practice it allows of. such. modifications and that' the v'mo'difica tions admit of control because the limits. 'of their action and effects may predetermined by. calculation-by means of the equa,

-tions and formulas which yI have derivedor by others deducible therefrom.

With

the purpose .in view of making casttions which establish the relations between the speed of rotation, the angle of inclination of the axis of rotation and the shape of the paraboloid formed, from which equations the requirements forv producing any desired casting which it is possible to produce by my process can be determined. .I have calculated the shapes and dimensions of many castings by the equations which are herein given and have subsequently made castings in strict accordance with the conditions imposed by my calculations. I

have found in every instance that lthe actual vcastings produced conformed' with remark- 'able trueness to my advance calculations.

In Figs. 1, 2, 3 and': there is'shown a machine which I- have found suitable for carrying out my process. I n these figures of the drawings, 1, represents a revoluble metal pi or tube which is provided 'with suitable lring collars, 3, '4, located near its front and upper end, 5. A tilting housing, l6, which has. trunnions, 7, supported .in 'bearings in' the sides of the stationary frame,'8, is provided for. the support of the tube,`1, and its driving motor. Radial thrust rollers, 9, for rotatably supportingl tube, 1,'are

rovided in thetilting housing, 6. 'En thrust rollers, 10, 11, suppored -by the tilting housing are provided to coact withthe' collars, 3, .4, upon the tube, 1, to retain` the rotating' tubc, 1,.

against longitudinal movement. ,`A motor, 12,y mounted upon the tilting housing, G, is employed for rotating the tube,by means ofthe beflt, .13. It will bevunderstood that any other convenient driving means may be employed for rotating the tube, 1, and

'that any convenient means may 'be used for ascertaining and controlling the of rotation.

Near the rear end fof the tube, 1, 'which' is also the lowerend when the -tube is tilted,4 is the stationary frame or guide, 14, in.

which there is mounted and adapted to slide verticall a housing, 15,' which is' provided with ra i'al'thrust rollers, 16, upon which the tube, '1, rotates.

,The uppermost rollers, 9 and- 16, have bearings in spring-held, adjustable boxes, 171 and 18, the springs, 19 and 20, serving to' maintain the rollers with yielding pressure upon'the rotating tube, 1. Thehousing, `15,

is provided with trunnions, 21, which are adapted to slide in slots, 22, in the guides, 14. Attached to the trunnions, 21, by pivoted collars, 23, are the cables, 24, which extend upward and are connected with a device, 25, for raising and lowering the rear end of the tube, 1, in order to tilt the tube to the desired angle. To give added rigidity and added accuracy of setting to a known angle.

holes such as 26 may be drilled through the sides of the guides, 14, andthe rear housing, 15, and in like manner through the sides of the stationary frame, 8, and the front hous` ing, 6, in suclrmanner as to receive throughbolts, such as 27, with nuts, which, when drawn tight, serve to secure the several parts of the construction in perfect alignment in their inclined position.

The tube, l, is either lined with refractory material such, for instance, as asand mold of annular cross section, or, preferably, as shown in Fig. 2, receives a pipe or tube, 28, having a refractory lining, 29, the opening in the refractory lining being of theA shape which it is desired to give to the exterior of the casting to be made. therein.

The back or lower end of the mold is formed by a stop-off plate or plug, not shown, set at the desired distance from the front end of the mold so as to determine the length of the casting and secured in place by a rod that.v extends between it and yoke device, 30. The front or upper end of the mold is formed by an annular disc or plate of metal, 31,l which is secured to the flanged end of the tube, 1, by means of bolts, 32, and which may receive a lining or facing, 33. of refractory material.

In the operation of the machine to produce a casting by my process, the tube, 1 has iirst inserted into it the pipe 28, with its refractory lining, 29, which has been preheated to drive off the moisture that it may have contained. The tube, 1, is then tilted to the proper anglo for producing the desired casting, for instance, the angle at which the tube is shown in dotted lines at 34. The tube, 1, with its refractory lining is next brought to the desired speed of rotation by means of the motor, 12, or by any other means that may be provided for the purpose, the molten metal is then introduced-through the opening, 35, at the' upper end of the mold, andv is disposed by centrifugal force and gravity into the shape which it is made to assume by these forces.

The rotation is preferably continued until the metal has solidified.

The casting is afterwards removed from the mold and is then ready for machining or other treatment, or for use in its rough condition.

Fig. 18 shows in longitudinal section a casting suitable for making the separate cone of a submarine periscope tube. In this figure the scale of the drawing parallel to the axis of the casting is made much smaller than the transverse scale for the purpose of illustration.

Fig. 19'shows in longitudinal section a casting suitable for making a submarine periscope tube, with cone and cylinder cast together' in one piece, the casting being formed with a simple paraboloidal void.

Figj20, shows in longitudinal section a casting suitable for making a submarine periscope tube, the casting being made in the special modified manner I have elsewhere described. A portion of the void, in this case from the upper end, 36, down to, the point, 37, is of one simple paraboloidal shape and the portion from the point 37, down to the lower or stop-0E end, 38, is of another paraboloidal shape. It will be observed that the void formed in the casting shown Ain Fig. 20 is the resulting composite of a plurality of successively formed paraboloids. v i

In Fig. 18, therefractory material of the mold is indicated at, 39, by the area shaded in dotted section lines; the casting itself, 40, is indicated in section; the paraboloidal bore formed in the process of casting is indicated by the boundary lines, 41, and the outline of the finished cone, which is machined all over, is indicated in dotted lines, at 42.

In Fig. 19 the material of the refractoryV mold. is shown in dotted section lines at 43; the casting itself is indicated in section at 44; the paraboloidal void in the casting is indicated by the boundary lines, 45, andthe finished tube is indicated in dotted lines at 46.

In Fig. 20, the material of the refractory mold is indicated in dotted section lines at 47 the casting is indicated in section at 48; the upper portion of the paraboloidal void is indicated by the boundary lines, 49, extendingbetween the upper end, 36, and the point 37, of the casting; the portion of the paraboloid corresponding to the boundary lines, 49, which would bc formed except for the changing of the angle of inclination or of the speed of rotation o'r both during the process of casting is shown by the dotted" extension 50, of lines, 49; the virtual vertex of the paraboloid corresponding to" the boundary lines, 49, 50, is indicated at 51; the paraboloidal void formed after changing the angle of inclination or the speed of rotation, or both, is indicated by the boundary lines, 52, extending from the point, 37, to the vertex 53; and the finished tube to be machined out .of the casting, 48, is shown in dotted lines at, 54.

In Figs. 19 and 20, the longitudinal scale of the drawings ismade much smaller than the transverse scale in the same manner as in Fig. 18. .k

In Figs. 9 to 147inclus1\*e, of the drawings .axial sections .of paraboloids of equations from jl/:a'f:g

as would be suitable for asubmarine peri- -scopel tube.

cordance with my invention.

These figures illustrate the wide range of' castings that can be made in ac- In order that-those skilled in the art may better understand my invention, I 'herein give the mathematical proof of its theor)y together withthe derivation of the essential formulas which I have deduced which will` enable anyone to calculate inadvance the shape of the bore of the casting, the proper speed of rotation of theA mold for any given angle of inclination of its axis or thepropcr angle of inclination of the' mold for any given speed of rotation, and the quantity of metal required to form. the casting.

' be noted here that Q is the Gal The proof of the shape ofthe hollow or void formed in liquid material rotating about an inclined axis' in a mold or recep and lts top tacle having its bottom closed .closed as shown in Fig. 2 to within a suicient radial distance from the axis of rotation lto prevent the egress of the liquid is as follows Referring to Fig. 5,

let'A be `any particle of lmolten metal or of other liquid material .in theV inclined mold, the angle of inclination 'of 4the aXis,-Y, 'of the mold with the horizontalbeing S.` Let thev weight of the particle be Gr. pounds. Let P and Q components of G in directions respectively parallel to and at right angles to,` the axis of the mold and'in a vertical plane through lthe axis, Under these conditions P-:G sin S.`

The orce Q may b'e disregarded present consideration because mold and the particle A revolve, the action of Q toward the mold becomes in each revolution. alternately and equally positive and negative so Athat tive .to the mold and does not v affect the position which the surface of the molten metal will assume within the mold. It may force whichdetermines the minimum 'speed at which the mold must be revolved inorder to hold the in the metal against the 'sides of the mold. Con- A, it will readily7 be4 sidering the particle understood that when A and the mold are revolving, the -force Q must be ovemcome by the centrifugal force when A is at the highest point of its revolution in order that the particle may be prevented from. falling away from 'the upper sideor` the mold.

upon the particle A the first last being very narrow and deep or- -Therefore a line drawn be the` when the Q. compensates itself -rela` fore. A's in Fig. Let u's now consider the forces which actbeen established and while the mold and A are rotated at constant speed about the ,in clined axis of the mold. A diagram of these forces is shown in Fig. G.

Referring to Fig. 6, as the machine and the particle A revolve, A is acted upon by two forces which together determine the shape assumed by the surface of the molten metal. These two forces are P and the centrifugal force C. Their resultant is thel force .N Whose direction, if the particle' A be at a point in the surface of the metal, must be normal to the surface at that point.'

at right angles to the direction of t e force' N, and in the plane determined by the point 'A and the axis of rotation, as shown must be a tangent to the curvethat is formed by the surface of the metal. This tangent will make an angle' Twith the direction .of the axis of the mold.

From the construction,

Where M is the mass of the pa velocity in eetper second and r the radius of rotation in feet. Substituting in the equation for the value of tan T the valuesl of P and C found above gives v i G sin S 'Gr sin'S lian T -I- Since or the accelerationdue tolgravity,

tun Y v2 41f It be the revolutions per sccond,-then. 0:2 'It FR Therefore, l I gr sinS'ggsinS v' n tanTnrwRlifRzr (l) From equation (1) maybe `found the angle T for' any inclination and any speed, .but only for individual radii of thebore when through the oint A in Fig.

ria

such are' known and without determining` i where those radii will be. formed;

. In Fig. 7, let the axis 'of rotation be the be its coordinate axis. In this figurethe point A is taken atv (m, and the angles S and T are the same as be- 6, the straight line drawn through (w,-y) is, under the conditions, a tangent to ythe curve that forms the surface- Y.orv

of the metal, consequently the inclination of this line to the axis X must be the slope of the curve at (a, y), and that slope is equal to the tangent of the angle H.

From the construction, nza.,

But

, o 1 1 lian H 00h T im Hence,

tan H: 47T.R-7

g sln S The differential equation of the curve may now be written from which may be derived the Aequation of c the curve 2791121122 g sin S (2) Rza/:2 sin S From equation, (2), the curte for any4 particular case may .be put into the form g/:aaa2 the constant, a, being equal to` 3523i 1 *causait2 gsinSOr sinSy l Now, if the value of a be kept unchaned, then for any 'assigned value of R or a corresponding value must exist for S or R.

It is evident there-fore that the equationof the curve may be madeindependent of both l and S, provided that other determining factors are given'. This may be done as follows:

Referring to Fig. 8, ylet the parabola there shown be represented `by the equation g/:aazl .The following relations hold true for any two points (w1, QI/1)l and (m2, y2) located on this parabola:

`"Now, ai, and za, 'areidentical tol two radii, say fr, and r2 `1n the boreor void of the cast- Ling, at 'two different'points along its' axis .to` those i enumerated. above.

If Lz-z/z--yl the last equation may bev re- 'o Inserting this value for (a) in yzax2 we have:

Lanz

Equation (3) is the equation of the parabola in terms of any two radii of the bore of the casting and the axial distance betwen those radii, and is the equation most commonly usedto determine the shape of .the bore'.

Equations (2)y and (3) are the main equations for the solution of the problems of my process and `both of these' equations give identical results. Whether equation (2) or equation (3) or both of them should berused depends only upon the known factors or conditions which are given, from which to find the remaining conditions necessary to successfully produce the casting in practice.

Dewi/ved equations showing relations Abe-l tween spoedv and inclination for any "o given parabola.

VSolving (2) 4 for R, we have f 4R=1.2755Y/i/-g-- r(4) This may be conveniently written amena/Tus 5)V Remembering also the `value of (a) whichv is used in equation (3) we may write.

' L sin S R- azz-swf (6) i Equation (4) gives the revolutions per second in terms of the sine of the'angle of inclination, any radius of the bore expressed in feet, and the' axial distance in feet of that .radius from the vertex of the arabola. Equation (5) gives the' revolutions per second in terms of the sine of the angle of inclination and the roeiiicient, a, of 'm2 in the equation ofthe parabola, and is the equation most commonly used to obtain speed and angle relations. i

Equation (6) rgives the revolutions per second in terms ofy the sine of the angle of inclination, any two radii of the bore .ex-

ieet `between those radii. 'lransposing ,(4), (5) andA (6), gives the angle interms of the revolutions per second, the other conditions ycorresponding exactly The corresponding values for the angles follow:

pressed in feet, and the axial distance in i `"Voltone computations.

To obtain the volume of metal needed to make a' iven casting, the volumeof the void may deducted from the total volume of the mold. The volume of the mold may be found by addin to e'ther the volumes of its arts. If t e rustum of a cone enters 1nto this, the following volume formula-may be used:

vrdldz) 4 s where A,L and A2 are the areas of the two bases, h is the altitude of the frustum and el, and d, are the diameters of the two bases res ectively.

he volume of the void willl be the volume of so much of the paraboloid as is contained between the `front and back ends of the mold. The position of the vertex of the paraboloid relative tothe back end of the mold is preferably to be first known and may be found byV making the proper substitutions in equation (2) or equation (3) or, better., directly'in the equation y:

- am after.(a) is known.

If Vrepresents the volume'of the paraboloid between the front and back endsof the mold when the vertex lies behind the back end of the mold, then 1.5708 V= a (yf-21.*)4 4(11).

If the vertex lies within'the mold, y, becomes zero 'and 1. i V= 5708er. (12) To illustrate the practical application of these equations to the determination of the.

conditions that should be observedin making a casting by my process, I herein show the solution of a concrete case such as might occur in practice.

Referring to Fig. 19 of the drawings, let it be required to provide a casting from which .to make a submarine periscope tube such as is shown in dotted outline and longitudinal section at 46` Let the finished dimensions of the required tube be: outside diameter 4 inches at m, and 6% inches at n. and 0; overall length 14 feet, for 10 feet of which, from o to tn., the tube is to be cylin-v drical, and for the remaining 4 feet, from n, -to m., uniforml tapered; wall thickness, 1/2 inch. In or er to produce a finished tube conforming to these measurement, let

there be required arough casting such as i's indicated at 44 in Fig. 19, of the following dimensions: outside diameter 41,4 inches at p and m, and 6% inches at n, o, and g; in-

- side diameter 2% inches at p, and 5,1/4z inches at q; over-all len h 14 feet 6 inches,- of which 14 feet is the ength of'the finished casting, 2 inches an4 extra allowance lin length at the small end p, and 4 inches an extra allowance in length at the large end y.

Examination of the data discloses that for this casting the measurements given are reducible to the requirements of equation (3), viz, two radii of the bore and the axial distance between them. Expressed 'in feet .the radii ofthe desired inside diameters,

2% and 51,4 inches' respectively, 'will be 221:0.1146 ft., and w21-0.2187 ft., and the len th L of the cast-ing equals 14.5 ft. Intr hence y=418a12 is the equation of a parabola ucing these values into equation (3):

which, if revolved .about its axis would generate a paraboloid, part of which would be of the shape and size of the bore which would be obtained in the rough casting.

It now remains to fix the speed and angle relations, which may .be done through equa- 'tions (5) or (8). 'If the angle of inclination be assigned, equation.(5) will deter-.`

mine the speed of rotation while if the speed of rotation be assigned, equation (8) will` determine the angle of inclination. In either case. the value of a, 418, as found above,l will also be used. Accordingly if'the assigned angle of inclination be 10 degrees,

its sine, 0.1736, and the value, 418, found for a, may

`be substituted in equation (5), yielding or S sin0.14704 4of rotation of 600 revolutions per minute.

To determine the volume of the mold, the volume of the parts may be determined separately and then added together:

Cubic inches.

p to m (cylinder) 28 m to n (frustum of cone) 1160 n to q (cylinder) 4437v Total volume of molds.- 5625 To determine the volume of the bore of the casting, equation (11) may be used.

The values of y, and y2 may be found by substituting back into 3]:418 m2 the values of and m2 already used, 0.1146 and 0.2187 respectively. Accordingly,

1:41a a 011462255 3,224.18 w 0.21872. 20.0

It may be noted herethat'yl, or.-5.5 feet is the distance fromthe back or smaller end of the casting to the virtual vertex of the paraboloid, as from p to 55 in Fig. 19, and

that having found it, the value of y, may

This is in cubic feet, and isequal to 2401 cubic inches.

To determine the quantity of metal in t-he rough casting, its volume may first be found, and then its weight. Its volume may be obtained by finding the'ldiference between the volumes of the mo-ld and. of the bore, 5625 and 2401 cubic inches respectively, or 8224 cubic inches. If the weight per cubic inch of the metalemployed be 0.30 pound, the Weight ofthe casting would then be 3224 times 0.30 pound, o r 967 pounds,

In using my process the specific gravity of the .material from Which a casting is to be made is a matter of indifference so far as concerns the relations between the speed of rotation, the angle of inclination and the shape of the bore of the casting. Whether aluminum, lead, or' any other substance be` used, is therefore a m-atterof` indiference everywhere in the computations, except only in the operation ofdeducing the weight of the casting from the value found for its volume, at which point, obviously, -acbrrect value for the weight per unit of substance should be used. The proof that these relations and the equations representing"'them are thus independent of the specific gravity of the material is seen in the derivation of equation 1) where the mass, M, of the particle, has been shown to disappear.

Having thus described my invention, I claim and desire to .secure by Letters Patent: l

1. In apparatus for casting metal tubes and the like having paraboloidal hollow said -mold the requisite inclination to produce Within the casting a cavity of'the de` sired paraboloidal form.

2. In apparat-us 1for casting metal tubes and the like having paraboloidal hollow bores formed under the joint action of centrifugal force and gravity, a revoluble mold, a support therefor, bearings for said revoluble mold carried by said support, and means for revolving said mold, the axis of rotation of said mold being inclinedv to the horizontal.

3. In apparatus ofthe class described, a mold revolubly mounted in a tilting housing, a motor mounted on said tilting housing, driving connections between said motor and said mold, and means for tilting said mold and said housing.

4f. In apparatus of the class described a mold revolubly mounted in a housing, a support for said housing, a motor mounted on said housing in driving connection with said mold. and means for tilting said mold and said housing.

5. In apparatus of the class described two ,y stationaryT supports, a tilting housing mounted on one of said supports, a vertically adjustable tilting housing mounted upon the other of said supports, and a revoluble mold carried in bearings in sai housings.

6.` `In apparatus of the class described, a stationary support, a tilting housing mounted on sald` support, a vertically` adjustable tilting housing. a revoluble mold carried in bearings in said housings, and means for rotating said mold.

"7. In apparatus of the class described, a stationary support, a tilting housing mounted on said support, a vertically adjustable tilting housing, a revoluble mold carried in bearings in said housings, means for rotating said mold about its axis and means for inclining said axis of said mold.

8. In apparatus of the class described, a stationary support, a tilting housing mounted upon said support, a vertically adjustable tilting housing, a revoluble mold carried in bearinfrsin said housings, means for rotating said mold about its axis, means for inclining said axis of said mold, and means for securing said vertically adjustable housingin its adjustedposition.

9. In apparatus of the class described, a revoluble mold, two bearings for said mold, one of said bearings being mounted for tilting about an axis transverse to the axis of rotation of said mold andthe other of said lmarings being mounted for tilting about an axis transverse to the axis of rotation of said mold, and means for vertically adjusting one of said bearings. bores, a .mold the interior of which has the i 10. In apparatus of the class described a revoluble mold, two bearings for said mold, 1

both of said bearings being provided with trunnlons having their axes transverse to the axis of rotation of said mold, one of said bearings being vertically adjustable.

11,- 111 a centrifugal casting machine, an

elongated revolubl'e mold, bearings therefor,

horizontally spaced bearing supports and adjustable means whereby said bearings may be soheldin their supports in different vertical relations as to give the desired inclination 'to the mold, A

` 12. The process of forming a plurality of paraboloidal voids in objects cast from molten metal or other solodifiable fluid material which consists of placing a quantity of said fluid material in a hollow mold, the volume of said fluid material Ybeing insufficient to fill said mold, imparting a rotating movement tothe fiuid material in said mold whereby a paraboloidal void is formed in said material about the axis of rotation thereof, continuing the rotation of the material in this position until la portion of the material is solidified, then inclining the axis tation, continuing the rotation of the material about said inclined axis until a ortion of the material has solidified, t en changing the inclination of said axis and continuing the rotation of the material until another portion of it is solidified.

14. Theprocess of forming hollow tubularobjects which consists of imparting to `a quantity of solidifiable fluid material a' rapid rotating movement'about an axis, confining the said materialwithin radial limits bue. permitting it to flow longitudinally of" said axis so that due to said rotation it forms within `said radial limits a' hollow shell of non-uniform diameter, the internal cavit of said shell being a paraboloid symmetrical=with the axis of rotation, continu ing said rotation at a constant speed until a portion of said material is solidified, then changing the speed of rotation and continuing it at said changed speeduntil another portion of the material has solidified. 15. The method of making periscope tubes or the like of cast metal which loon- -sists of centrifugally casting a long parabof.

loidal void in a metal cylinder-the contour of the longitudinal crossv section of said void approximating the desired contour of the finished tube with allowance for internal finish, and .subsequently finishing the inner surface to the desired dimensions and contour;

16.' Ina .centrifugal casting machine a revol'uble hollow shaft, bearings supporting said shaft, said bearin s being adjustable to incline the axis of sai "shaft, a hollow mold in said shaft, the axis of said shaft and said. l

mold'coinci'ding, said shaft and said mold being open at their upper ends, and driving meansl or said shaft. 1

- 17. In a centrifugal casting machine a revoluble hollow shaft, bearingsl supporting said shaft, said bearings being adjustable to incline the axis of said shaft, a hollou1 mold in said shaft, thevaxis ofsaid shaft' and said mold coinciding said shaft and vsaid mold being open at tieir upper ends,

to drive the same in any of its adjusted positions. V

In testimony whereof I affix my signature.

ROBERT F; WooD.

and driving means for said shaft operahle 

